Open hearth furnace



H. M. MURPHY OPEN HEARTH FURNACE Filed July 26, 1932 2 Sheets-Sheet l INVENTOR [2E/v/erflf%eP/1K BY M 0 lgMM ATTORNEYS July' 11, 1933. H. M. MURPHY OPEN HEARTH FURNACE INVENTOR 2 Sheets-Sheet 2 ATTORNEYS I BY MI mm Qw. NM N g N fi'E/VEYM .M-UEPHK Filed July 26, 1932 al-Pi Patented July 11, 1933 STATES HENRY M. MURPHY, OF FAIRFIELD, ALABAMA.

OIEN HEARTH FURNACE Application filed July 26, 1932. Serial No. 624,803.

This invention relates to metallurgical furnaces and aims to provide structural improvements whereby important economies are effected in both the initial cost and cost of maintenance.

Que object of the invention is to provide at each end of an open hearth furnace, a singleliue structure which serves as the sole means of communication between the furnace slag pocket and the checker chambers of a regenorator at that end of the furnace.

Hcretoforo, when using producer gas or other gas of relatively low thermal value which requires pie-heating for efficient combustion, it has been practically the universal practice to provide double-compartment regenerators, such regcnerators having one chamliicr for the preheating of gaseous fuel and another chamber for the preheating of the air supplied for combustion. With such furnaces has been essential to provide two slag pockets at each end of the furnace and to provide a double flue connection so that the gas and air streams would be separately conveyed through the and air chambers, respectively, of the regencrators, through the douh e flue connection, through the two slag pockets and into the furnace chamber.

When using liquid fuel such as tar or oil for firing a furnace it has been, so far as I am informed, almost the universal practice in this art to follow the old conventional furnace design including the use of two slag pockets at each end of the furnace and two lines connecting the respective slag pockets with the two checker chambers of each regenerator.

When separate flue connections between gas and air checker chambers and gas and air pockets are en'iployed, it has been customary to build the connecting structure between the regenerators and the slag pockets at the end of the furnace with two roof arches, one over the gas fine and the other over the air fine.

I have discovered when tar or other liquid or semi-liquid fuel is to be used, which does not require preheating in a regenerator, that certain important economies can be effected in furnace construction and maintenance.

An important feature of the invention is the provision of a connecting structure between a double furnace regcnerator and a single slag pocket at each end of the furnace, such structure having a single connecting flue covered at the top by a single arched roof.

The above and more detailed features of the invention will be fully apparent from the following specification when read in connection with the accompany drawings.

In the drawings Fig. 1 1s a horizontal section through an open hearth furnace showing the associated regenerators and the connecting flue structure in top plan;

Fig. 2 is a fragmentary plan view with parts sectioned to show the connection between the single slag pocket and the two lon gitudinal checker chambers of a regenerator at one end of the furnace;

Fig. 3 is a vertical section on the line 33 of Fig. 1 illustrating the connection between the furnace slag pocket and the regenerator associated therewith;

Fig. 4; is a vertical section on staggered line -le of Fig. 1, the left side of the figure being sectioned through the slag pocket at the left end of the furnace, the right side of the figure being sectioned through the improved v single flue connecting the regenerator and slag pocket at the right end of the furnace;

Fig. 5 is a fragmentary vertical section through the single flue connection on, the plane indicatedby line 5 5 of Fig. 1;

Fig. 6 is a vertical section through one of the regenerators as indicated, for example, by section line 66 of Fig. 1.

Referring in detail to the drawings, 10 represents an open hearth furnace as a whole resented as a whole at 36 and 38. Both are substantially the same and a description of one will suffice for both. Each flue structure includes substantially upright converging side walls 40 which support a single fantail arched roof 49.. Thus the single fines 4.4 and 4.6 at the opposite ends of the furnace are provided.

The regenerators 32 and 34 are each formed with a longitudinally extending division wall 4-8, thus dividing each regenerator longitudinally into two checker chambers 50 and 52. These chambers are filled wth conventional forms of checker work forming a multiplicity of channels through which the air supplied for combustion passes on its way to the furnace and through which the outgoing spent products of combustion pass on their way to the stack.

As is clear from the detail view, 2., the division wall 48 terminates at 54c and'therefore it does not extend through the connecing fine 44 as has heretofore been the case. Heretofore the common practicehas been to provide separate gas and air slag;- pockets at each end of the furnace and to continue the wall 48 to the wall separating the two slag pockets, thus providing separate passages leading respectively to each of the checker chambers 50 and 52. These plural passages of the prior practice have each been provided with a separate arched roof.

The division wall heretofore used in the passage l i generally extended to the slag pockets of the furnace and was exposed on both sides to extremely high temperatures. This old division wall in practice was fre quently badly eroded and cut away by the outgoing gases thus allowing the skew brick to settle and finally causing the two overhead arches formerly used to cave in. Moreover. the old practice of providing a dividing wall in the connecting structure between the reg'enerators and the slag pockets required considerable floor area. \Vithout such a division wall I provide at each end of the furnace a single flue connection ft-4E6 of generous area. in cross-section. This reduces the velocity of the outgoing gas and is favorable to a settling;- of oxidized slag-like particles. It is highly advantageous to keep down the quantity of slag particles carried overinto the regenerators because they tend to choke up the spaces between the checker brick work in the regenerator chambers.

The regrenerators 32 and 3 as shown in Figs. 2 and 3 are provided with transverse division walls 56 and 58 defining an upright passage 60. The outgoing tasesfrom the regenerators 32 and 34; pass to ducts 62 and (is having: conventional control dampers 6G and 68 therein. Any usual or suitable air control valves 70 and 72 are provided for controlling the influx of air to the respective regenerators. The ducts 62 and 64 both commui'iicate with a duct 74 leading; to the usual stack 76. The duct 7% is provided with a suitable stack damper T8. The outgoing gases of combustion from opposite ends of the furnace are alternately passed through regenerators 32 and according to common practice which involves periodically reversing the direction of travel of gases through such furnaces, which is accomplished by altcrnately opening and closing air valves 70 and 72, cooperating with dampers 66 and ('38. Air valves 70 and 72 are shown as saucer type valves that open and close openings through the top of fines.

lnasinuch as the rcgenerators 32 and 34 are divided by the longitudinally extending wall 48 into separate checker chambers, it will. be apparent that. if necessary. the furnace -an be readily changed over from one adapted to burn tar fuel to one utilizing producer gas fuel. This change can be .effccted by merely extending division walls through the single flue connections 44 and f6 and building suitable division walls in slag pockets so as to provide separate gas and air passages and slag pockets, respectively, at each end of the furnace.

lVhile the division wall 48 is not an essential requirement when using tar or other l quid or semi-liquid fuel, such wall, however, is advantageous even though combustion air is passed through both checker ch ambers of each reg'enerator, because the double chamber regenerator tends to preventthe air from chanmelingf through only a restricted area of the regenerator. Thus. a better distribution of the air stream through the rca'enerator is effected thereby securing greater uniformity than if only one large single chambered regenerator were to be em ployed.

The oblique arrangement of the regenerators is advantageous in furnace installation having my improved single flue connection, because the upright walls of this fine connection can be conveniently disposed in such position that they converge from each regenerator toward the slag pocket, and thus provide for a smooth and easy flow without abrupt chance in direction for the outgoing gases on their way to the stack through the ducts 69 and 6%.

The provision of the single flue connection between the slag pocket of the furnace and each regenerator effects a material saving in the first cost of installation due to the elimination of the division wall heretofore universally used. It also provides a con nection having longer life than that heretofore used since there is no division wall or support wall subject to destruction. There is also ef'ected a saving of time heretofore required to tear down and replace such division wall. The single flue connection also provides more slag room than was provided in structures heretofore used. A further advantage is that in the single flue connection slower gas velocities are attained than is the case in prior conventional practice. This cuts down heat losses heretofore caused by the coating of the checker work and thus provides a far more efiicient and quicker heat transfer from the outgoing gas to the checkers and on the other hand from the checkers to the incoming combustion air.

While I have described with great particularity the specific embodiment of the invention herein illustrated, it is not to be construed that I am limited thereto since Various modifications and changes in arrangement may be made by those skilled in the art without departure from the spirit and scope of the invention as defined in the appended claims.

lVhat I claim is:

1. In combination with an open hearth furnace and a respective regenerator communicating with each end of the furnace having a plurality of checker chambers therein so separated by common vertical partition means as to place said chambers in parallel, a connecting structure between each regenerator and the furnace having only a single flue communicating with one end of the furnace and said plurality of checker chambers.

2. In combination with an open hearth furnace and a respective regenerator communicating with each end of the furnace and having a plurality of checker chambers therein so separated by common vertical partition means as to place said chambers in parallel, a connecting structure between each regenerator and the furnace having only a single flue communicating with one end of the furnace and said plurality of checker chambers the top of said structure comprising a single arch defining the top of said flue.

8. In combination with an open hearth furnace having only one slag pocket at each end thereof, a regenerator having a plurality of checker chambers therein so separated by common partition means as to place said chambers in parallel at each end of the furnace and a structure at each end of the furnace including a single flue providing the sole means of communication between each respective slag pocket and its associated regenerator.

at. In combination with an open hearth furnace having a slag pocket and a regenerat-or having a plurality of checker chambers therein so separated by common partition means as to place said chambers in parallel at each end thereof, respective flue structures each including upright walls extending from the outer walls of each regenerator to each slag pocket and a single arch roof spanning the space between said upright walls, the latter walls and roof forming part of the sole flue connection between each respective slag pocket and the regenerator associated therewith.

5. In combination, an open hearth furnace having a slag pocket at each end thereof, obliquely arranged regenerator converging in plan as they recede from the furnace and a respective connecting structure having only one fine therein between each regenerator and each slag pocket.

6. In combination, an open hearth furnace having a slag pocket at each end thereof, obliquely arranged regenerators converging in plan as they recede from the furnace and a respective connecting structure having only one flue therein between each regenerator and each slag pocket, said structure including upright side walls which converge from the regenerator toward the slag pocket and a fantail arched roof spanning the space between said upright side walls.

In witness whereof, I have hereunto signed my name.

HENRY M. MURPHY. 

